1. Field of the Invention
The present invention relates to an information processing device using a protocol to acquire a setting value to be used in network communication.
2. Related Background Art
A representative network protocol is Transmission Control Protocol (TCP)/Internet Protocol (IP).
TCP/IP involves layered network protocol groups, with the following standardized protocol groups: on the network level there are Internet Protocol (IP), Internet Control Message. Protocol (ICMP), Address Resolution Protocol (ARP) and the like; on the transport layer there are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).
When network communication is performed using TCP/IP protocol, it is necessary to uniquely determine logical addresses on the network, which are called IP addresses. An IP address is made of 32 bits (4 bytes), and generally they are written in 8-bit increments, such as “150.61.146.1.00” (0x963d9264).
For an information processing device to set its own IP address, the IP address can be set according to an input from a keyboard or operation panel, for example (e.g., Japanese Patent Application Laid-Open No. 2001-306474).
When the information processing device does not include a keyboard or the like, or when a user wants to manage the IP addresses of multiple information processing devices together, there is a method of using protocols called Dynamic Host Configuration Protocol (DHCP), BOOTP or RARP. The information processing device acquires the IP address from a server on the network, and sets the IP address as its own (e.g., Japanese Patent Application Laid-Open No. 2001-268095).
DHCP is a protocol defined in RFC2131, and is a protocol in which a BOOTP protocol is expanded.
Once the information processing device which serves as the DHCP client is turned on, it then sends out a DHCP Discover packet. In the case where a DHCP server is present on the network, the DHCP server sends back a response to the Discover packet.
The information processing device sends a Request packet requesting the IP address to the DHCP server which sent back the response packet. In response to that request, the DHCP server selects, from a group of IP addresses being managed by the DHCP server, an IP address that is not being used by another information processing device, and lends that IP address to the information processing device subject to a usage limit. The information processing device uses the IP address which is subject to the usage limit (lease time), and performs network communication.
When the usage limit is about to reach its end, the information processing device sends a Request packet requesting extension of use of the IP address to the DHCP server. Provided there is no problem, the DHCP server lends the IP address with a new limit.
Furthermore, when an information processing device which is a client is turned on, it makes an IP address inquiry to the DHCP server and performs the aforementioned procedure to acquire an IP address, whereby it can use the IP address to perform network communication.
In an Operating system (OS) such as Windows® for example, information about network-related operation settings is stored in a system database called a registry.
FIG. 15 is a diagram showing an example of a registry storing the operation settings information. In columns 1501 names of construction information keys are registered. In columns 1502 values corresponding to the construction information keys (below, “key values”) are registered. When the key value in the Enable Dhcp registry is set to “1”, the DHCP client service supplied with the OS becomes activated. When it is set to “0”, the DHCP client service becomes deactivated.
When the DHCP client service has been deactivated, the IP address, the subnet mask and the gateway address which were manually set by the user are. stored as the key values in the IP Address registry, the Subnet Mask registry, and the Default Gateway registry, respectively.
When the DHCP client service has been activated, IP address, the subnet mask and the gateway address which the DHCP client service acquired automatically from the DHCP server are saved as the key values in Dhcp IP Address registry, the Dhcp Subnet Mask registry, and the Dhcp Default Gateway registry, respectively.
When the DHCP client service has been activated, the information processing device performs the network communication in accordance with the key values in the Dhcp IP Address registry, the Dhcp Subnet Mask registry, and the Dhcp Default Gateway registry, respectively. When the DHCP client service has been deactivated, network communication is performed in accordance with the key values in the IP Address registry, the Subnet Mask registry, and the Default Gateway registry, respectively.
Here, the DHCP client service supplied with the OS has a restriction that in order to activate the DHCP client service, the key values in the IP Address registry, the Subnet Mask registry and the Default Gateway registry must be “0.0.0.0”.
In other words, when the key values of the IP Address registry, the Subnet Mask registry and the Default Gateway registry are other than “0.0.0.0”, even if the DHCP client service is active, the DHCP parameters from the DHCP server will not be reflected in the Dhcp IP Address registry, the Dhcp Subnet Mask registry, and the Dhcp Default Gateway registry, respectively. The key values of the Dhcp IP Address registry, the Dhcp Subnet Mask registry and the Dhcp Default Gateway registry will be overwritten with the key values from the IP Address,registry, the Subnet Mask registry, and the Default Gateway registry, respectively.
Thus, once a user inactivates the DHCP client service and manually sets the IP address, the subnet mask, and the gateway address, and after that, if the user does no more than simply activate the DHCP client server, the DHCP parameters from the DHCP server will be ignored.
In order to prevent the DHCP parameters from the DHCP server from being ignored, the user by itself must manually set the IP address, the subnet mask, and the gateway address to “0.0.0.0”.
Alternatively, other than a DHCP client service provided by the OS, such a new DHCP client service described above must be created.
Therefore, even in the case where the DHCP client service provided by the OS has the above-mentioned restriction, it is preferable that the settings be configured based on the DHCP parameters from the DHCP server while using the DHCP client service having the above-mentioned restrictions.